Endogenous ClO Research Articles

Long-wavelength red-emitting ClO− fluorescent probe for visualizing inflammation and drug-induced renal injury

Hypochlorous acid (ClO−), a member of the reactive oxygen species (ROS) family, plays an important role in regulating physiological processes and maintaining homeostasis in the body. However, abnormal ClO− levels in the human body have been associated with a variety of pathological conditions, encompassing inflammation and kidney diseases. In this work, we have developed a novel fluorescent probe, RDNClO, specifically tailored for the sensitive detection of ClO−. RDNClO was synthesized through modifying N - (7 - (2 - carboxyphenyl) -3- (dimethylamino) - 5,6 - dihydro - 10H - benzo[c]xanthen - 10 - ylidene) - N - ethylethanaminium (RDNOH) with 1-naphthaloyl chloride moiety. Spectroscopic analyses reveal that RDNClO exhibits outstanding performance characteristics, including high selectivity, a rapid response time of <25 s, and an ultra-low detection limit of 3.7 nM. Additionally, RDNClO has demonstrated exceptional capabilities in detecting ClO− in real water samples and rapidly identifying ClO− in environmental samples, utilizing agarose as a carrier. It effectively monitors both endogenous ClO− levels in HeLa cells and exogenous ClO− levels in HEK293T cells. Furthermore, RDNClO has excelled in tracking fluctuations in ClO− levels, including in Escherichia coli, the mouse model of arthritis induced by k-carrageenan, and a mouse model of cisplatin-induced renal injury. The development of RDNClO not only establishes a robust theoretical foundation for investigating the pathogenic mechanisms of renal injury but also presents a promising tool for advancing research in this critical area.

A dual-response fluorescent hemicyanine probe for the detection of mitochondrial hypochlorite and viscosity based on ESIPT/AIE and TICT

Viscosity and hypochlorite (ClO−) are two important factors affecting the physiological activity and function of mitochondria. Hypochlorite (ClO−) is a vital reactive oxygen species, and endogenous ClO− acts as an important germicidal oxidant in the immune system at low concentrations. While, fluctuations in viscosity can cause mitochondrial dysfunction that is linked to several diseases. We herein report on a hemicyanine-based probe (BDTB-PA) for the detection of hypochlorite (ClO−) and viscosity. The probe exhibits a very low fluorescence background in an aqueous solution due to twisted intramolecular charge transfer (TICT) and blocked excited-state intramolecular proton transfer (ESIPT). In a viscous solution, the TICT of the probe was inhibited, generating a strong emission at 580 nm. In contrast, upon treatment with ClO−, the phenylboronic acid pinacol ester group of probe BDTB-PA was removed, and the hydroxyl group was released, activating the ESIPT process. Coupled with its aggregation-induced emission (AIE) characteristics, the product of BDTB-PA with ClO− exhibited a distinct emission at 540 nm. As such a solution of the probe BDTB-PA exhibited a distinct fluorescent color change from colourless to green under UV light with the addition of ClO−. More importantly, probe BDTB-PA was used for monitoring ClO− and viscosity in the mitochondria of living cells, plants and zebrafish.

Water-Soluble Photoluminescent Ag Nanoclusters Stabilized by Amphiphilic Copolymers as Nanoprobe for Hypochlorite Detection

Luminescent Ag nanoclusters (Ag NCs) are a promising probe material for sensing and bioimaging applications. However, the intrinsic obstacle of poor water stability and photostability greatly restrict their practical application in biological systems. Herein, we report the intracellular hypochlorite (ClO−) detection with amphiphilic copolymer-modified luminescent Ag NCs with good biocompatibility and photostability. The Ag NCs were synthesized by using chemically inert hydrophobic ligands and then modified with an amphiphilic (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(poly(ethylene glycol))-2000]) (DSPE-PEG-2000) and sodium dodecyl sulfonate (SDS) for phase transfer. It was found that the approach of the removal of organic solvents during the phase transfer has remarkable influences on the properties of the Ag NCs, including their size, luminescence property, and aqueous stability. Furthermore, the silver core of Ag NCs could be oxidatively damaged by ClO−, thereby causing photoluminescence (PL) quenching. The ClO−-induced PL quenching was specific over the other common reactive oxygen species (ROS) as well as some common interferences. Finally, they have been successfully applied as a fluorescent nanoprobe for detecting exogenous and endogenous ClO− in living cells.

Self-ratiometric photoluminescence carbonized polymer dots with Junas structure for hypochlorite selective sensing

The Janus structure of carbonized polymer dots (CPDs) is characterized by an independent yet interdependent core and shell structure, potentially enabling them to function as a self-ratiometric photoluminescence (PL) sensor. However, to our best knowledge, the current lacking understanding and development of the Janus structure of CPDs lead to the unfortunate loss of its position as PL sensors that could have supported life analysis to some extent. Therefore, it is crucial to comprehensively explore the structural characteristics of CPDs and furtherly develop its potential as self-ratiometric sensors. Herein, green and red double-emitting CPDs has been rationally designed and synthesized, incorporating a distinct core-shell structure to create a self-ratiometric sensor for hypochlorite (ClO−). Leveraging the low toxicity and high-water solubility of CPDs, we have successfully achieved exogenous and endogenous ClO− sensing in cells. This approach offers a novel strategy for developing CPDs-based sensors and sets the stage for a more in-depth exploration of the Janus structure of CPDs.

Ratiometric fluorescent probe with AIE characteristics for hypochlorite detection and biological imaging

It is very important and highly valuable to detect ClO− in samples and living cells with accuracy and speed. In this work, a novel fluorescent probe NA was prepared from 4-bromo-1,8-naphthalic anhydride by acylation reaction and Suzuki coupling reaction and used for the detection of ClO−. Thiomethyl serves as the recognition group for probe NA, while naphthalimide serves as fluorescent chromophore. The probe exhibited an extremely pronounced blue shift from yellow to blue fluorescence within 1 min after the addition of hypochlorite (ClO−). The probe demonstrates high sensitivity to ClO− with a limit of detection (LOD) of 1.22 µM. Also, probe NA demonstrates excellent selectivity and immunity to interference. Additionally, simple fluorescent test strips containing probe NA were prepared in this study, enabling rapid detection of ClO− in water samples. And NA had been effectively used to image endogenous and exogenous ClO−fluorescence in living cells. The results suggest that probe NA has significant potential for portable detection and biological applications.

Levonorgestrel protected Au10 cluster for hypochlorite sensing in living organisms

BackgroundHighly reactive oxygen species (ROS) could lead to serious damage in living cells and are associated with many diseases like cancers. Metal cluster with strong fluorescence has great potential in biosensing and many thiolate ligands-protected clusters have been applied in ROS sensing. ResultsIn this work, we synthesized levonorgestrel protected Au10 cluster with specific sensing ability for highly ROS via crystal transformation from Au8 cluster, demonstrating the significance of inner core structure on detecting performance. The detection limit of Au10 cluster for ClO− could reach as low as 0.1 μM. This fluorescent probe not only achieving detection of exogenous ClO− in living cells and zebrafish, but also successful imaging of endogenous ClO− in HeLa and HepG2 cells. SignificanceIn comparison to previously reported cluster-based sensors for ROS, this work proposes a different reaction mechanism of metal nanoclusters for ROS detection (breakage of gold-alkynyl bond and oxidation of alkynyl group). This provides new directions for designing specific ROS probes and broadens the applications of metal clusters in disease diagnostics.

A Ratiometric Fluorescent Detection Platform Using G‐CDs@[Ru(bpy)3]2+ for the Specific Detection of Hypochlorite and Live Cell Imaging

AbstractHypochlorite (ClO−), an essential reactive oxygen species (ROS) in physiological processes, is identified to be closely connected with oxidative stress and related diseases. Meanwhile, ClO− is a commonly‐used disinfector for water treatment, and in public places, under acidic conditions, it's easily decomposed into hypertoxic chlorine gas. Since the strong oxidizing property of ClO−, many oxidizing agents may disturb the ClO− detection. Specific and accurate detection of ClO− with superior sensitivity is a challenge. In this work, a sensing platform for rapid, sensitive, and specific ClO− detection is constructed using green fluorescent carbon dots (G‐CDs), with a linear detection range of 0.5–11 µm and a detection limit of 0.233 µm. Moreover, introducing a red fluorescent tripyridinium ruthenium ([Ru(bpy)3]2+) as a reference, a ratiometric fluorescence nanoprobe G‐CDs@[Ru(bpy)3]2+ is prepared and shows favorable intracellular imaging of exogenous and endogenous ClO−. With G‐CDs@[Ru(bpy)3]2+‐based test paper microarrays and a color recognition APP, a smartphone‐based sensing system for point‐of‐care testing of ClO− is also fabricated. In summary, this work proposed a versatile and economical smartphone‐based sensing system that featured reliability and simplicity, and suggested its potential applications in environmental water quality monitoring and live cell imaging.

A dual-emission fluorescent probe for simultaneous detection of singlet oxygen and hypochlorous acid in lipid droplets

Singlet oxygen (1O2) and hypochlorite (ClO-) are two important reactive oxygen species. They coexist in living systems and can be interconverted in organisms, being involved in a variety of pathophysiological processes. Lipid droplets (LDs) are organelles that transport and store lipids, and 1O2 and ClO- tend to destroy unsaturated lipids, leading to lipid oxidation and causing a range of diseases. Here we proposed the first dual-response fluorescent probe DBCC that can simultaneously distinguish 1O2 and ClO- within LDs. The probe is almost non-fluorescent, while significant fluorescence enhancement can be observed in the blue and green channels after treatment with 1O2 and ClO-, respectively. With the excellent properties of high sensitivity, good selectivity and wide tolerance range, the probe DBCC has been successfully used to detect 1O2 and ClO- in HepG2 cells and zebrafish, and faultlessly realized endogenous and exogenous 1O2 and ClO- imaging in LDs. This work provides a powerful analytical tool for further investigating the levels of 1O2 and ClO- in LDs and associated diseases.

Hemicyanine-Phenothiazine Based Highly Selective Ratiometric Fluorescent Probes for Detecting Hypochlorite Ion in Fruits, Vegetables and Beverages.

Hypochloric acid (HClO) is a reactive oxygen species (ROS) that functions as a bacteriostatic and disinfectant in food production. Excessive levels of ClO-, however, have been linked to various health issues, including cardiovascular diseases (Halliwell and Gutteridge in Oxford University press, USA, 2015), arthritis, and neurodegenerative diseases (Heinzelmann and Bauer in Biol Chem. 391(6):675-693, 2010). Therefore, synthesizing highly selective and sensitive probes for rapidly detecting endogenous ClO- in daily foods is currently a popular research topic (Kalyanaraman et al. in Redox Biol. 15:347-362, 2018;Winterbourn in Nat Chem Biol. 4(5):278-286, 2008; Turrens in J Physiol. 552(2):335-344, 2003). Thus, we have developed two highly selective ratiometric fluorescent probes (Probe1 and Probe2) based on indole-phenothiazine to detect ClO- in common vegetables, fruits and beverages qualitatively and quantitatively. Moreover, Both Probe1 and Probe2 have shown good specificity and stability, with high fluorescence intensity and long duration (Feng et al. in Adv Sci. 5:1800397, 2018; Wei et al. in Angew Chem. 131(14):4595-4599, 2019; Baruah et al. in J Mater Chem B, 2022).

A novel hepatocyte-targeting fluorescent probe of rhodamine analogues to detect hypochlorite in lysosomes: Design, synthesis and evaluation

A novel hepatocyte-targeting and lysosomal-targeting fluorescent probe of rhodamine analogues MOR-HOCl-Gal was designed and synthesized. MOR-HOCl-Gal exhibited good sensitivity and selectivity towards ClO−, without interference from other reactive oxygen species, representative anions, and representative cations. MOR-HOCl-Gal could be oxidized by ClO− to generate an instantaneous dicarbonyl diimide, and then hydrolyzed and ring-opened to a conjugated structure with high fluorescence property, which is confirmed by MS, 1HNMR and DFT calculations. Low toxic MOR-HOCl-Gal could distinguish hepatoma cells from other tissue cells, and selectively monitor endogenous and exogenous ClO− in liver lysosomes. The success of MOR-HOCl-Gal imaging in the zebrafish suggests that the aimed probe has the potential to visually monitor the presence of ClO− in vivo, and is expected to become a new effective diagnostic tool for liver related diseases.

A reaction-based bright red-emitting fluorescence probe for hypochlorite detection and its biological application

Monitoring the fluctuations of endogenous ClO−in vivo is very important to understand the physiological roles of ClO−and the mechanisms of ClO− relevant diseases. Herein, a new fluorescent probe, RhB-FL exhibited excellent sensitivity and anti-interference for ClO− detection, and the detection limit was as low as 4.8 × 10−7 M. Furthermore, RhB-FL was effectively applied to detect ClO− in cells.

Fluorescent Biomass-Based Platform for Detection of ClO- in Cells and Water-Soluble Systems.

The generation and presence of excessive hypochlorous acid derivative ionic form (ClO-) could cause various diseases, such as arteriosclerosis, DNA damage, and cardiovascular illness. It is a critical need to develop a highly sensitive sensor for reliable detection of ClO- in cells and water-soluble systems. In this work, a hydroxyl group has been introduced into the compound 2-amino-3-(((E)-4-(2-(2-(2-hydroxyethoxy)ethyl)-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)benzylidene)amino)maleonitrile (NDC) to increase its solubility in water, at the same time, the hydrazone unit was designed as a specific recognition group for the "off-on" fluorescence probe of ClO-. The probe NDC presents high selectivity, sensitivity, anti-interference, and low detection limit (67 nM) for ClO-. The recognition mechanism that ClO- breaks the C=N bond and forms the fluorescent compound 4-(2-(2-(2-hydroxyethoxy)ethyl)-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)benzaldehyde (ND-3) has been confirmed by time-of-flight mass spectrometry. The probe NDC presents a good performance in the actual test of water samples and can be designed as the test papers for the quick and convenient detection of ClO- range from 0 to 1 μM. Moreover, the practical application was demonstrated by the successful imaging of endogenous and exogenous ClO- in HeLa cells. Our fluorescent biomass-based platform opens vast possibilities for repeatability, sensitivity, and selectivity detection of ClO- in cells and water-soluble systems.

An AIE probe for simultaneous monitoring of endogenous and exogenous hypochlorite and Zn2+ at dual channels in living cells.

Zn2+ and ClO- may be associated with a variety of pathologies, and their simultaneous measurement is crucial for disease diagnosis and environmental protection. In this work, we synthesized an independent AIE probe, HNTE, through a one step reaction. The probe HNTE displayed a distinctive fluorescence color change from deep yellow to blue for ClO- and to green for Zn2+. More importantly, the probe HNTE could simultaneously detect endogenous and exogenous ClO- and Zn2+ in living cells colorimetrically via the blue and green channels.

Fluorescent imaging and smartphone detection of ClO- using sensors based on trifluoromethylquinoline-substituted pyranonitrile

In the field of novel fluorescent sensors, achieving rapid and sensitive tracking of target substances has become an urgent imperative. Applying this technology to the detection of biomarkers for biological diseases holds profound practical significance. Hypochlorous acid (HClO) is a significant reactive oxygen species (ROS) within biological systems. Aberrant metabolism of HClO can result in disruptions of physiological functions and oxidative stress, consequently influencing the development of various diseases. In this context, our study has successfully developed a novel fluorescent probe named W-4a, which employs trifluoromethyl quinoline as a substitute for traditional pyranonitrile compounds, enabling the rapid (<40 s) and highly sensitive (UV limit of detection: 1.62 μM; fluorescence limit of detection: 0.14 μM) detection of ClO-, during the detection process, ClO- effectively activated the fluorescent probe and showed a distinct red fluorescent signal at 687 nm. Furthermore, the W-4a probe exhibits excellent biocompatibility and excels in both exogenous and endogenous ClO- detection imaging within cells, Co-localization experiments indicate that probe W-4a effectively targets the Golgi apparatus. Additionally, in conjunction with the W-4a probe, we have devised a portable smart detection method for hypochlorous acid in environmental settings, which holds the potential to serve as a flexible and potent tool for monitoring environmental toxicity.

Synthesis and application of hypochlorite mediated acylhydrazone fluorescence probes.

Hypochlorous acid (HClO/ClO- ) is one of the important reactive oxygen species (ROS). It acts as a second signaling molecule within and between cells and is an indispensable active molecule in living organisms to regulate physiological and pathological processes. In this article, two fluorescent probes (PTF and PTA) for highly selective fluorescent recognition of ClO- were successfully synthesized based on the ICT mechanism by condensing phenothiazines with two hydrazides via the hydrazide structure (). PTF can identify different concentrations of ClO- in two steps. Due to its ClO- two site recognition, the probe exhibited good selectivity (specific recognition of ClO- over a wide concentration range), a fast time response (rapid recognition in seconds), a sufficiently low detection limit (3.6 and 11.0nM), and large Stokes shifts (180 and 145 nm). Furthermore, the recognition of ClO- by contrasting probes with different substituents exhibited different fluorescence changes of ratiometric type and turn-off. PTF successfully achieves the detection of exogenous and endogenous ClO- in aqueous solution and living cells.

A unique phenothiazine-based fluorescent probe using benzothiazolium as a reactivity regulator for the specific detection of hypochlorite in drinking water and living organisms

As a common disinfectant and an essential reactive oxygen species (ROS), hypochlorite (ClO−) plays vital roles in both water treatment and cell metabolism, but its abnormal level can cause serious harm to human health. Therefore, quantifying ClO− level in drinking water and living organisms is extremely significant. Herein, we decorated different cationic heterocycles on phenothiazine core to construct three fluorescent probes for ClO−. According to the results, only benzothiazolium moiety reasonably adjusted the electron cloud density at sulfur atom of phenothiazine core for the specific oxidation with ClO−, thus endowing the prepared probe PT-BT with a perfect selectivity for ClO−. Meanwhile, PT-BT exhibited a low detection limit (38 nM) and a fast response (within 20 s) toward ClO−. Furthermore, this probe was utilized to fabricate a ready-to-use test strip, which could quantitatively measure ClO− level in real water samples by a portable smartphone sensing platform. Notably, PT-BT targeted mitochondria efficiently, and successfully visualized endogenous ClO− in living cells and zebrafish larvae. Especially, PT-BT was able to monitor the dynamic change of ClO− level in inflammatory mice. These results strongly manifested that probe PT-BT was a promising tool for detecting ClO− in drinking water and living organisms.

Hantzsch Ester Modified Asymmetric BODIPY Probe with Ultra‐high Sensitivity for Ultra‐fast Detection of Endogenous Hypochlorite in Living Cells

Comprehensive SummaryHypochlorite (ClO–) is an important reactive oxygen species produced by the immune system to fight off invading pathogens, but its over‐expression can interfere with normal physiological process and induce serious diseases. Although a variety of molecular probes have been reported for detecting ClO–, the development of advanced fluorescent tools with faster response and higher sensitivity to precisely monitor ClO– remains a challenge. In this work, two Hantzsch ester (a derivative of 1,4‐dihydropyridine) derived fluorescent probes MeDHP‐BCl and MeDHP‐PhBCl were constructed based on asymmetric BODIPY‐matrix. These probes exhibit significant fluorescence turn‐on in the ultra‐sensitive (detection limit &lt; 1 nmol/L) and ultra‐fast response (≤ 5 s) to ClO–. The reaction has been determined to be a highly selective N‐chlorination of Hantzsch ester which cannot be activated by various common bioactive species, including nitric oxide (NO) that could oxidize Hantzsch ester under aerobic physiological conditions in most reports. MeDHP‐PhBCl possessed a relatively longer fluorescence emission wavelength and higher quantum yield after activation, while more notably, MeDHP‐BCl displayed lower cytotoxicity and more remarkable fluorescence increment in the response to ClO–, enabling selective and precise visualization of endogenous ClO– over‐expression in living RAW264.7 cells.

A colormetric and ratiometric AIE probe for imaging endogenous and exogenous hypochlorite

Herein, we designed a potent ClO− probe named ETMC, which exhibited aggregation-induced emission (AIE) characteristic in solid state and water/EtOH binary solvent. Probe ETMC exhibited an colormetric from yellow to blue and ratiometric response to ClO− with high selectivity and sensitivity, and a low detection limit of 3.66 × 10−7 M. Moreover, probe ETMC could be applied to visibly and quantitatively detect the different concentraction of ClO− in test paper. Importantly, probe ETMC could effectively detect endogenous and exogenous ClO− in living A549 cells by an outstanding ratio signal change. Also, the sensing mechanism of probe ETMC for ClO− was confirmed by FT-IR, 1H NMR, HRMS, DLS, TEM and DFT calculation.

A Simple ICT-Based Fluorescent Probe for HOCl and Bioimaging Applications.

Over the past few decades, drug-induced liver damage (DILI) has become a serious public health problem due to drug abuse. Among multifarious reactive oxygen species, mounting evidence attests that ClO- has been used as a potential biomarker in DILI. In this work, a new "turn-on" fluorescent probe 1 was designed and synthesized by modifying 4'-hydroxybiphenyl-4-carbonitrile (dye 2) with N, N-dimethylthiocarbamate as a response site for detecting ClO-. Probe 1 displayed a low detection limit (72 nM), fast response time (30 s), wide pH operating range (6-8), great tissue penetration, large Stokes shift (125 nm) and 291-fold fluorescence enhancement at 475 nm in the mapping of ClO-. Probe 1 could trace amounts of exogenous and endogenous ClO- with high sensitivity in MCF-7 cells and HeLa cells. Expectantly, the fluoxetine-induced liver injury model is successfully established, and probe 1 has been used for detecting the fluctuation of ClO- levels in the mouse model of fluoxetine-induced liver injury. All in all, probe 1 with its high specificity, good biological compatibility and liver tissue penetration ability is expected to assist with the early diagnosis of DILI and the clinical screening of various new drugs. We expect that probe 1 could be efficiently used as a powerful molecular tool to predict clinical DILI and explore molecular mechanisms between molecules and disease.

A novel colorimetric fluorescence probe for the sensitive and selective detection of hypochlorite and its bioimaging in living cells

Hypochlorite (ClO−) is a well-known redox regulator among reactive oxygen species and plays a crucial role in bacterial disinfection and body immunity. Therefore, there is a high demand for an analytical technique to monitor ClO− under physiological conditions. Herein, a novel fluorescence probe, RES-DPPT, was developed for detecting ClO−. This probe employs diphenylphosphinothioyl unit as the recognition group and resorufin as the fluorescent platform. RES-DPPT has high sensitivity and specificity, rapid response, and wide pH tolerance for monitoring ClO−. Additionally, RES-DPPT undergoes colorimetric and fluorescence color changes in the solution, which can be observed by the “naked eye.” Furthermore, RES-DPPT is successfully able to detect exogenous and endogenous ClO− in living cells.